PROCESSOR-SDK-J721E: what about function some flash chips on J721 EVM?

The J721E can boot from many different types of memory interfaces.  The EVM provides mechanism for software/users to test/use many of those boot memory types.

Note the reference designators you are referring are on the SK-TDA4VM not the J721E EVM. 

U44:  QSPI flash memory, optional boot memory for the processor

U57:  EEPROM memory for the TPS25750 USB Power Delivery device.  This EEPROM stores configuration for the power device, and should not be touched.  Any updates could cause the board to fails (as board power may no longer be provided if TPS25750 device is not configured correctly)

U2:  Configuration EEPROM used by TI software to determine board type, revision, etc - for correctly setting SDK configuration during boot.  It is NOT part of the processor boot, but part of TI's software configuration during boot.

thanks robert, I see,it seem we can remove U44 and U2, so how can we write  U57(EEPROM )  for some  power configuration if used our customed board? Any manual  about it?

For programming of the TPS25750, see its programmers guide: https://www.ti.com/lit/pdf/slvubz4

For additional information on programming/setup of the TPS25750, I suggest you submit a new E2E ticket so it can be routed to correct persons.

thank a lot! we will try it